Orthopedic devices for the feet (hereinafter sometimes called "orthotics") are well known, and have been used by laypersons and podiatrists for many years. Orthotics of this type range from a simple arch support to a custom formed support for the foot. It has been estimated that 50% of the population could benefit from some form of shoe orthopedic device to improve support and balance for the foot.
Since the feet are the foundation on which the rest of the body is supported, foot misalignment can result in many forms of discomfort for the patient. Symptoms which have been known to develop from such misalignment are plantar fasciitis, hammertoes, bunions, achilles tendonitis, and others. Misalignment can also cause or exacerbate knee, hip or back problems.
In an ideal situation, orthotics can cure two forms of misalignment. First, the orthotic should match the sole of the foot to the ground and, second, the orthotic should bring the remainder of the body into proper alignment with the foot. It will be appreciated that the feet, legs and upper body represent a closed kinetic chain in which a change at any one point can affect the remaining points. Obtaining proper alignment of the foot with the ground can be simplified to "bringing the ground up to meet the foot", while obtaining proper alignment of the foot with the rest of the body involves adjusting the relative position of the foot to the legs.
Many pre-formed orthotics are available to remedy a variety of patient maladies relating to posture, stance and gait. Most such pre-formed orthotics are formed of a polymeric material and sold in a variety of sizes and shapes, with the expectation that one or another of the pre-cast shapes will be close enough to the patient's needs that the orthotic will be acceptable.
However, in most such instances, the fit--and thus the amount of improvement--provided by the mass produced orthotic is far less than perfect. Typical problems involve the conformity of the orthotic to the sole of the foot, which affects the uniformity of support, as well as the amount of correction provided. Since only a few sizes of mass produced orthotics can be justified from an economic standpoint, this requires the patient to accept a significant amount of compromise in comfort and fit, and leads many patients to abandon use of the pre-formed orthotic.
Custom fitted orthotics are also available, but typically are very expensive. In the conventional approach, a custom orthotic is constructed by starting with a complete cast of the foot. Such custom orthotics are frequently, though not always, done under the supervision of a podiatrist. The impression which results from the casting is then sent to a laboratory where the custom formed orthotic is developed from the impression. As a result, the custom orthotic typically conforms to the sole of the patient's foot much better than a mass produced orthotic. Such custom orthotics, however, have two serious limitations. While the fit is much better in most instances, if an error is made either in making the initial casting, or making the orthotic from the casting, the resulting orthotic is substantially useless. Second, and often more important, changes in the patient's physiology require that the custom orthotic be recast. This latter limitation with the existing art can also affect patients using mass produced orthotics, and is particularly applicable to children. Children typically outgrow custom inlays in approximately one year. Given the expense of such custom orthotics, the economic burden can become substantial for either type of recasting.